Re: [Xen-users] bridge interfaces in dom0

[Jaroslaw Zdrzalek <jz@xxxxxxxxxx>]

Am Montag 13 November 2006 16:17 schrieb Steve Feehan:
> On 11/10/06, Jaroslaw Zdrzalek <jz@xxxxxxxxxx> wrote:
> > Am Donnerstag 09 November 2006 23:11 schrieb Steve Feehan:
> 
> > In dom0 you have physical interfaces, the naming is pethX,
> > and you have virtual ones, which are these named ethX.
> > Neighter the physical ones nor the bridges shoud have ip
> > configured. If you really nead ip traffic going from dom0 to
> > your domUs configure ip on ethX in Dom0 und DomU.
> > It is sufficient.
> 
> Yes, I understand this.
> 
> > > I thought that the interface would have to merely be "up" but not
> > > necessarily have an
> > > IP address configured since bridging is done at layer 2. But alas, if
> > > I don't configure
> > > an IP address on dom0 the bridge seems to not be usable from a guest 
> > > domain.
> > It shoult not happen. Did you have read the howto for multiple bridges:
> > at the bottom, starting with:
> > "With Xen 3.0 the best method for additional bridges is t..."
> > http://wiki.xensource.com/xenwiki/XenNetworking
> 
> Yes, that is what I based my configuration on. Here is my custom network 
> script:
> 
> #!/bin/sh
> /etc/xen/scripts/network-bridge $@ bridge=xenbr0 netdev=eth0 vifnum=0
> /etc/xen/scripts/network-bridge $@ bridge=xenbr1 netdev=eth1 vifnum=1
> /etc/xen/scripts/network-bridge $@ bridge=xenbr3 netdev=eth3 vifnum=3
> 
> And this works fine as long as the virtual interfaces (eth0, etc.) have IP
> addresses configured.
> 
> Actually, let me state this more completely:
> 
> My custom network-script works if the phsical interfaces have IP addresses
> BEFORE xen starts.
> 
> And when I say it works, I mean that:
> 
>  * bridges are created
>  * the virtual interfaces exist in the guests
>  * AND they are usable.
> 
> It's the last point that is the important part. When I don't configure
> IP addresses
> on the physical interfaces in dom0 BEFORE starting Xen the bridges are still
> created and the virtual interfaces exist in the guests, but they're
> not usable. And
> by not usable I mean if I configure them with an IP address and try to ping 
> from
> the guest I get "network unreachable" errors. At least, that is what I
> recall. This
> is all getting a bit fuzzy in my memory after the long weekend. I need
> to go back
> and reproduce the problem again.
> 
> > > My motivation for this is that dom0 has 4 interfaces which could be on
> > > 4 networks. I
> > > didn't want to assign IP addresses for dom0 on ALL of these networks.
> > You need 4 bridges, no need to configure any ip in dom0
> 
> Yes, this is what I think too. I will try and reproduce the problem
> and follow up with
> the result.

I just tryed out your scenario.
I have two physical interfaces and also two bridges.
I use debian sid, it stores the network config in /etc/network/interfaces.
I renamed that file and also /etc/init.d/xend.
Then I restartet and none of the interfaces in dom0 was configured.
I started xend and it came up as usual (all cables was attached).
I started an hvm guest and it have had networking up & running.

sorry, but at least on my debian it is working as expected ;-)

I attach a log from the session.

cheers
Jaroslaw

> 
> Thanks,
>

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